The present invention relates to a process for removing mineral impurities, such as metal oxides, from coals and shale oil structures. The invention allows for the recovery of carbons and hydrocarbons of high purity from coal and shale oil. The mineral impurities removed from the coals and shales can also be recovered as useful by-products.
During World War II, the German chemical industry was able to prepare low ash carbon from coal in a process based on the reactions of non-oxidizing acids such as hydrofluoric and hydrochloric acids. However, these processes were not economically viable due to the high costs of obtaining those acids, and there was the further disadvantage of the contamination of the carbon product by the residue of those acids and their chemical derivatives, arising from the processes then being used. These prior art processes are also not viable at the present time as a result of the necessity of protecting the environment from contamination by waste products, particularly those containing fluoride salts. Present day pollution control laws in many countries prohibit the use of the processes as were used by the Germans during the 1930's and 1940's.